What is BDE?
BDE stands for basic daylight exposure, also known as the Sunny 16 rule.
it's the standard for finding the best exposure on a typical sunny day
I have just come to understand it and I know a lot of people do not understand it. BDE tells us what fstops will be best to use with the shutter speeds. obviously this is more important if you manually adjust your 35mm camera settings. Hopefully with this write up I can help some people understand.
let's start with the basics
BDE = 1/iso @ F16
for those who don't know iso is film speed
this involves the use of the iso table which is
3 6 12 25 50 100 200 400 800 1600 3200 6400
4 8 16 32 64 125 250 500 1000 2000 4000 8000
5 10 20 40 80 160 320 640 1250 2500 5000 10000
now another thing we need is your shutter speeds. heres the typical shutter speeds
1sec, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000
as you move ---> you are reducing light that comes into the lense
and then the list of apertures
f1, f1.4, f2, f2.8, f4, f5.6, f8, f11, f16, f22, f32, f45, f64, f90
as you move <-- you increase the amount of light that comes into the lense
NOW the fun part
Say we take Kodak triX film with the iso of 400 and we want to use the shutter speed of 1/125sec
there for we have the beginning of the BDE formula
.......1/125 @ f(?)
now to find the correct aperture we go back to the ISO chart
3 6 12 25 50 100 200
400 800 1600 3200 6400
4 8 16 32 64 125 250 500 1000 2000 4000 8000
5 10 20 40 80 160 320 640 1250 2500 5000 10000
as you move right or left horizontally we more a full stop
as you move up and down in the columns you move a 1/3 of a stop
because we are moving from 400 to 125 we are obviously moving down one row and left two colums. therefore we are opening 2 1/3 stops
so if we remember that the bde = 1/iso @ f16
a 2 1/3 of a stop down from f16 = f 22 2/3
therefore our bde for
Kodak triX (iso 400)
shutter speed 1/125sec @ f22 2/3
remember you take the iso from the chart
and then find the shutter speed we want to use on the chart. then count the amount of stops it takes for you to go from the iso to the shutter speed
it took me a few hours alone and 2 people to try to explain it to me so any questions at all about this stuff please feel free to contact me and I can try to explain it better.
I am attending Brooks Institute of Photography so i will quickly be learning all the fun stuff.
you can AIM me at aPerfectFallacy and email me at
Tadashiphoto@gmail.com
just remember that BDE will in most cases give you the best exposure on a sunny day usually around the times 9am-3pm assuming its a perfectly sunny day :w00t
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